JP2003129860A - Thermoelectric variable composite gas turbine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermoelectric variable composite gas turbine which can correspond to the change of heat demand and does not cause the deterioration of performance at normal operation. SOLUTION: This gas turbine has a co-generation system in which power is generated from a generator 8 driven by a standard gas turbine 1, and also a steam (h) is generated by recovering waste heat from an exhaust gas (g) discharged from the turbine 1. An auxiliary gas turbine 17 is installed in conjunction with the turbine 1 and further, a steam mixer 6 is installed in a high pressure air supply path 5 extending from a compressor 2 composing the turbine 1 to a combustor 3. When the demand of steam decreases, surplus steam is introduced into the steam mixer 6, and a gas mixture (i) of the surplus steam (h) with high pressure air (d') and a fuel (e') are fed into a combustor 11 of the auxiliary gas turbine to be burned. By the combustion gas (f') from the combustor 11, the auxiliary gas turbine 17 is driven to assist power generation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermoelectric variable synthesis gas turbine.

[0002]

2. Description of the Related Art In general, a cogeneration system exhibits the best energy saving effect when the mutual demands of heat demand and electric power demand are met.

However, there is a case where the heat demand changes more significantly than the electric power demand, and the heat energy must be wasted. Under such circumstances, the effect of introducing a cogeneration system is low.

As a measure, there is a gas turbine capable of supplying a part of generated steam to a gas turbine combustor to increase generated electric power and suppressing supply of thermal energy.

[0005]

However, this system can be operated according to the demand situation of electric power,
Since the amount of introduced steam increases in addition to the combustion gas passing through the turbine, the turbine passage area is wider than that of a normal turbine that does not perform steam injection.

Therefore, the performance at the normal operating point is sacrificed and the performance is degraded, and the operating point of the compressor shifts due to the injection of steam, leading to surging, and in the worst case, the operation stops. there is a possibility.

The present invention has been made in order to solve such a problem, and an object of the present invention is to reduce the performance at a normal operating point even though the turbine can cope with a change in heat demand. It is to provide a thermoelectric variable synthesis gas turbine that does not occur.

[0008]

In order to solve the above problems, the present invention is configured as follows.

(1) In a cogeneration system for generating steam by recovering waste heat from exhaust gas discharged from the standard gas turbine while generating power with a generator driven by the standard gas turbine, the standard gas turbine is used. Auxiliary gas turbine is installed at the same time, and a steam mixer is provided in the high-pressure air supply path from the compressor that constitutes the standard gas turbine to the combustor, and when the demand for steam is reduced, excess steam is added to the steam mixer. Introducing steam, supplying a mixed gas in which excess steam and high-pressure air are mixed and fuel to a combustor of an auxiliary gas turbine for combustion, and driving the auxiliary gas turbine by the combustion gas for power generation Variable thermoelectric synthesis gas turbine.

(2) The thermoelectric variable synthesis gas turbine according to (1), wherein a generator common to both the standard gas turbine and the auxiliary gas turbine is driven.

(3) The thermoelectric variable synthesis gas turbine according to (1), wherein the standard gas turbine and the auxiliary gas turbine respectively drive their own generators.

(4) The thermoelectric variable synthesis gas turbine according to (1), wherein the exhaust gas discharged from the standard gas turbine and the auxiliary gas turbine is supplied to a common waste heat boiler.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 1 is a standard gas turbine, and this gas turbine 1 is composed of a compressor 2, a first combustor 3 and a normal turbine 4. A steam mixer 6 is provided in the high pressure air supply path 5 from the compressor 2 to the first combustor 3.

In this standard gas turbine 1, the air d is
It is introduced into the compressor 2, where it is compressed into high pressure air d ′, which is introduced into the first combustor 3 via the vapor mixer 6.

On the other hand, the fuel e is supplied to the first combustor 3, mixed with the high-pressure air d'which has already been described, and vigorously combusted, and the combustion gas f is introduced into the ordinary turbine 4,
The turbine 4 is rotated. The rotation of the turbine 4 is normally transmitted to the generator 8 via the compressor 2 and the speed reducer 7, and the generator 8 generates electric power.

The exhaust gas g discharged from the normal turbine 4 is introduced into the waste heat boiler 9 and waste heat is recovered.
The steam (process steam) h generated in the waste heat boiler 9 is supplied to the next step (not shown).

When the demand for steam is reduced, the excess steam is superheated by the superheater 10 and then introduced into the steam mixer 6 as superheated steam h ', and mixed with the high pressure air d'. Then, generally, the inflow gas pressure in the normal turbine 4 increases.

In order to avoid this, a control valve 13 and a shutoff valve 14 are provided in the path 12 from the steam mixer 6 to the second combustor 11, and the opening degree of the control valve 13 is adjusted according to the rate of pressure increase. To maintain a constant pressure. The waste heat boiler 9 includes a preheater 15 and a superheater 16.

Therefore, the surplus gas (mixed gas of superheated steam h'and high-pressure air d ') i flows into the second combustor 11.
The fuel e'is supplied to the second combustor 11 and is mixed with the surplus gas i to burn violently. This combustion gas f '
Is introduced into the auxiliary turbine 17 and rotates the turbine 17. The rotation of the auxiliary turbine 17 is transmitted to the speed reducer 7 via the clutch 18, and the output of the auxiliary turbine 17 and the output of the standard gas turbine 1 described above are combined and output via the speed reducer 7 as a total output. It is transmitted to the generator 8 and high power generation output by the generator 8 is obtained. here,
An auxiliary gas turbine 19 is configured by the second combustor 11 and the auxiliary turbine 17.

On the other hand, the exhaust gas g'exhausted from the auxiliary turbine 17 is supplied to the waste heat boiler 9 for evaporation.

In the above description, the two turbines 4 and 1
7 and one generator 8 have been described, the present invention is not limited to this. For example, as shown in FIG. 2, two turbines 4 and 17 and two generators 8 and 20 are used. The same effect can be obtained by using and. In addition, in the figure, 21 and 22 have respectively shown the reduction gears. For other devices, the same reference numerals are given to the same devices, and detailed description will be omitted.

Next, the operating condition of the standard gas turbine (FIG. 1) will be described with reference to FIG.

In the normal operation of the standard gas turbine 1, the compressor 2 and the normal turbine 4 are matched at the point A on the standard compressor characteristic curve Rs. Under this circumstance, the injection steam amount Gs from the waste heat boiler 9 is taken into consideration, so that when the control valve 13 in FIG. 1 is “closed”, the pressure rises as the standard gas turbine passing gas amount increases. , The amount of air supplied from the compressor 2 is the standard compressor characteristic performance R
Moving on s, the amount of air decreases to G1 at point c.

The injection steam amount Gs is Gs + G1 (= G), which is indicated by the intersection c'of the standard compressor discharge pressure CDPs' associated with the steam injection determined by the standard gas turbine resistance line Ls.
t).

Since point c exists at a point beyond the surging line of the compressor 2, the gas turbine becomes unstable in operation and is dangerous. The control valve 13 operates so as to maintain the standard gas turbine compressor rated discharge pressure CDPs by adjusting the opening so as not to become CDPs'.

Next, the resistance line La of the auxiliary gas turbine alone
Is generated and is generated as an independent output of the auxiliary gas turbine 17 corresponding to the air volume Ga at the point aa intersecting the CDPs. Both points are points aaa of the turbine combined resistance line Lc, that is, the point where the above-mentioned injected steam amount Gs is added to the standard air amount. Here, the amount of air corresponding to the combined turbine output (= Go + Gs) is shown (however, the amount of fuel supplied to the auxiliary gas turbine combustor 11 is ignored).

After all, the air volume obtained by adding the injection steam volume Gs to the air volume Go of the standard gas turbine enables stable operation of the compressor in the CDPs state.

Since the amount of injected steam changes according to steam demand, the auxiliary gas turbine 17 is forced to have a partial load, and because of its small capacity, it can be operated while maintaining a constant inlet pressure as much as possible. preferable. Therefore, the compressor 2 of the standard gas turbine 1 is provided with an air flow rate variable control mechanism 23 '(see FIG. 2) such as an inlet guide vane or a variable vane, and the auxiliary turbine 17 has the same air volume variable control mechanism 2'.
3 (see FIG. 1).

By applying this cogeneration system, the output was improved by about 70% and the efficiency was improved by 32% with respect to the standard machine.

In FIG. 3, Ga is the auxiliary turbine air flow rate, and Ls' is the virtual resistance line of the standard turbine.

[0032]

As described above, the present invention is a cogeneration system for generating steam with a generator driven by a standard gas turbine while recovering waste heat from exhaust gas discharged from the standard gas turbine. In the above, a standard gas turbine is provided with an auxiliary gas turbine, a steam mixer is provided in a high-pressure air supply path from a compressor that constitutes the standard gas turbine to a combustor, and when the demand for steam is reduced, Introducing surplus steam into the steam mixer, supplying mixed gas and fuel in which surplus steam and high-pressure air are mixed to a combustor of an auxiliary gas turbine for combustion, and driving the auxiliary gas turbine by the combustion gas. Since it is used for power generation, it is a turbine that can respond to changes in heat demand, but performance will not deteriorate at the normal operating point. It has enabled stable operation.

[Brief description of drawings]

FIG. 1 is a schematic view of a thermoelectric variable synthesis gas turbine according to the present invention.

FIG. 2 is a schematic view of a thermoelectric variable synthesis gas turbine according to the present invention.

[FIG. 3] The horizontal axis represents the air flow rate and the vertical axis represents the compressor discharge pressure (CDP)
FIG.

[Explanation of symbols]

1 Standard gas turbine 2 compressor 3 combustor 5 High pressure air supply path 6 steam mixer 8 generator 11 Combustor of auxiliary gas turbine 17 Auxiliary gas turbine 19 Auxiliary gas turbine d'high pressure air e'fuel f'combustion gas g Exhaust gas h steam i mixed gas

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H02P 9/04 H02P 9/04 FPF Term (reference) 5H590 AA01 AA03 AA04 CA08 CA29 CE01 EB21 EB29 FA01 FA05 GA04 HA02 HA04 HA18

Claims (4)

[Claims] 1. In a cogeneration system for generating steam by recovering waste heat from exhaust gas discharged from the standard gas turbine while generating electricity with a generator driven by the standard gas turbine, an auxiliary gas is supplied to the standard gas turbine. A steam mixer is installed in the high-pressure air supply path from the compressor that composes the standard gas turbine to the combustor, and a surplus steam is introduced into the steam mixer when the steam demand decreases. However, a mixed gas of excess steam and high-pressure air and fuel are supplied to a combustor of an auxiliary gas turbine for combustion, and the auxiliary gas turbine is driven by the combustion gas for power generation. Variable synthesis gas turbine. 2. The thermoelectric variable synthesis gas turbine according to claim 1, wherein a generator common to both the standard gas turbine and the auxiliary gas turbine is driven. 3. The thermoelectric variable synthesis gas turbine according to claim 1, wherein a generator unique to each of them is driven by a standard gas turbine and an auxiliary gas turbine. 4. The thermoelectric variable synthesis gas turbine according to claim 1, wherein the exhaust gas discharged from the standard gas turbine and the auxiliary gas turbine is supplied to a common waste heat boiler.